Downlink Acquisition

1. A method comprising: receiving a plurality of symbols; detecting, from an autocorrelation of the received symbols, a guard interval representative of a receive/transmit transition gap (RTG); and verifying, based on a modulation type, whether at least one symbol positioned after the detected guard interval is a preamble.

2. The method of claim 1 further comprising: determining the modulation type, wherein the determined modulation type provides a value representative of whether the at least one symbol was transmitted using binary phase shift key (BPSK) modulation.

3. The method of claim 1 further comprising: determining the modulation type based on a first magnitude of at least one real component of the at least one symbol and a second magnitude of at least one imaginary component of the at least one symbol, the determination using a Fast Fourier Transform (FFT) of the at least one symbol.

4. The method of claim 3 , wherein determining the modulation type further comprises: determining the modulation type by calculating a ratio of the first magnitude to the second magnitude.

5. The method of claim 4 , wherein determining the modulation type further comprises: providing an indication that the at least one symbol is likely the preamble, when the ratio is greater than about 1.

6. The method of claim 1 , wherein verifying further comprises: determining the modulation type based on the following equation: R RI = ∑ k = 1 L PN - 1 ⁢ ⁢ ( real ⁡ ( O ^ ⁡ ( k ) ) ) 2 ∑ k = 1 L PN - 1 ⁢ ⁢ ( imag ⁡ ( O ^ ⁡ ( k ) ) ) 2 .

7. The method of claim 1 , wherein detecting further comprises: determining at least one distance between at least two peaks detected from the autocorrelation of the received symbols, the autocorrelation implemented as a cyclic prefix (CP) autocorrelation.

8. The method of claim 7 further comprising: indicating a location of the RTG, when the at least one distance exceeds a threshold.

9. The method of claim 8 further comprising; transforming the at least one symbol positioned after the location of the RTG.

10. The method of claim 9 , wherein transforming further comprises: transforming using a Fast Fourier Transform (FFT).

11. The method of claim 10 further comprising: compensating, before performing the transformation, for at least one of a frequency offset and a phase rotation; providing a timing estimation to enable the transformation; and searching for a preamble identifier by searching a set of preamble identifiers.

12. The method of claim 1 , wherein receiving further comprises: receiving the plurality of symbols as a complex signal comprising an I signal and a Q signal.

13. A system comprising: a processor; and a memory, wherein the processor and the memory are configured to perform a method comprising: receiving a plurality of symbols; detecting, from an autocorrelation of the received symbols, a guard interval representative of a receive/transmit transition gap (RTG); and verifying, based on a modulation type, whether at least one symbol positioned after the detected guard interval is a preamble.

14. The system of claim 13 further comprising: determining the modulation type based on a first magnitude of at least one real component of the at least one symbol and a second magnitude of at least one imaginary component of the at least one symbol, the determination using a Fast Fourier Transform (FFT) of the at least one symbol.

15. The system of claim 13 further comprises: a buffer; and a cyclic prefix autocorrelator for correlating at least one of the plurality of symbols.

16. The system of claim 13 further comprising: determining a timing offset representing phase rotation of the plurality of symbols.

17. An article comprising a non-transitory machine-readable medium embodying instructions that when performed by one or more machines result in operations comprising: receiving a plurality of symbols; detecting, from an autocorrelation of the received symbols, a guard interval representative of a receive/transmit transition gap (RTG); and verifying, based on a modulation type, whether at least one symbol positioned after the detected guard interval is a preamble.

18. The article of claim 17 further comprising: determining the modulation type, wherein the determined modulation type provides a value representative of whether the at least one symbol was transmitted using binary phase shift key (BPSK) modulation.

19. The article of claim 17 further comprising: determining the modulation type based on a first magnitude of at least one real component of the at least one symbol and a second magnitude of at least one imaginary component of the at least one symbol, the determination using a Fast Fourier Transform (FFT) of the at least one symbol.

20. The article of claim 19 , wherein determining further comprises: determining the modulation type by calculating a ratio of the first magnitude to the second magnitude.